Signals a process (created using proc_open()) that it should terminate. proc_terminate() returns immediately and does not wait for the process to terminate.
The optional signal is only useful on POSIX operating systems; you may specify a signal to send to the process using the kill(2) system call. The default is SIGTERM.
proc_terminate() allows you terminate the process and continue with other tasks. You may poll the process (to see if it has stopped yet) by using the proc_get_status() function.